Sunan an-Nasa'i, Hadith 2256 ⓘ
It was narrated that Saeed bin Al-Musayyab said: "The Messenger of Allah said: 'It is not righteousness to fast when traveling."' (Sahih) Abu 'Abdur-Rahman (An-Nasai) said: This is a mistake, and what is correct is the one that is before it. We do not know of anyone who followed up Ibn Kathir.
أَخْبَرَنِي إِبْرَاهِيمُ بْنُ يَعْقُوبَ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، عَنِ الأَوْزَاعِيِّ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لَيْسَ مِنَ الْبِرِّ الصِّيَامُ فِي السَّفَرِ " . قَالَ أَبُو عَبْدِ الرَّحْمَنِ هَذَا خَطَأٌ وَالصَّوَابُ الَّذِي قَبْلَهُ لاَ نَعْلَمُ أَحَدًا تَابَعَ ابْنَ كَثِيرٍ عَلَيْهِ .
also referenced under: Book 22, Hadith 167 (In-Book) & Volume 3, Book 22, Hadith 2258 (DarusSalam)